By Will Dunham

WASHINGTON, May 21 (Reuters) - Malignant brain tumors remain one of the deadliest types of cancer, but new treatments have extended the lives of patients a bit in the past decade, and researchers say further advances may be on the horizon.

This week's diagnosis of Massachusetts Democratic Sen. Edward Kennedy, a leading U.S. political figure for half a century, with a dangerous tumor called a glioma has focused international attention on brain cancer.

"There have been some advances in the treatment of this disease. I'm impatient for more. And I really feel that the advances we've had have been small, baby steps," Dr. Otis Brawley, chief medical officer of the American Cancer Society, said in a telephone interview on Wednesday.

For patients diagnosed with a glioblastoma -- an especially perilous tumor -- average survival time after diagnosis is 6 to 12 months, or 6 months without treatment.

Dr. Victor Perry, a neurosurgeon at the University of North Carolina School of Medicine, said these treatments generally have added weeks or months, not years, to the lives of patients with the most serious forms of brain cancer.

Experts say standard treatment may involve six weeks of relatively high-dose radiation coupled with a chemotherapy drug called temozolomide, sold by Schering-Plough Corp. <SGP.N> under the brand name Temodar.

Patients then get Temodar for six months or more, or until the tumor ceases to respond.

Brawley expressed hope that Genentech Inc's <DNA.N> drug Avastin soon may be a valuable addition to brain cancer treatment.

Results of a study announced last week showed Avastin, known generically as bevicizumab, improved survival for patients with recurring brain cancer. Avastin is a targeted therapy that starves tumors by stopping them from building tiny blood vessels.

BRAIN WAFER

Perry said another addition in treating malignant gliomas has been Japan's Eisai Co Ltd's <4523.T> Gliadel Wafer, a drug delivery device. A chemotherapy drug is infused in a polymer wafer that biodegrades over time. Doctors place it inside the brain at the site of the tumor and it releases the drug over two to three weeks.

The Gliadel Wafer can only be used if a tumor can be removed safely.

Experimental vaccines are aimed at encouraging the immune system to beat back cancer cells. One being studied is DCVax-Brain, a so-called personalized vaccine made by U.S. biotechnology company Northwest Biotherapeutics Inc <NWBO.OB>.

Dr. Michael Gruber of New York University and the Brain Tumor Center of New Jersey, who is involved in the study, said the vaccine is made by collecting a portion of the tumor and combining it with immune cells from the patient.

"Our hope would be to cure the tumor, but we've been trying to do that for 100 years. I think the realistic challenge is: can we put the tumor in remission for a long time?" Gruber said.

U.S. biotechnology company ImmunoCellular Therapeutics Ltd <IMUC.OB> also is studying a vaccine against glioblastoma.

The American Cancer Society said about 22,000 malignant tumors of the brain or spinal cord will be diagnosed this year in the United States, and 13,000 people will die. Worldwide, about 200,000 such cases are diagnosed annually. (Editing by Maggie Fox and Xavier Briand)

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